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Hello community! 

Recently, I ran into an issue where AIX backup jobs were taking longer than expected to start. After digging around, I came across a very useful Veeam KB article (KB2014) that suggests testing disk I/O to identify potential bottlenecks, especially useful when backing up to tape or dealing with performance inconsistencies.

I decided to try out one of popular tools for benchmarking and simulating disk workloads: DiskSpd (for Windows).

Step 1 – Install Disk Benchmark Tool

Make sure you have the following installed:

  • diskspd– Microsoft’s free disk performance tool for Windows.

Step 2 – Run DiskSpd on Windows

Here’s the command I used:

diskspd.exe -c25G -b512K -w100 -Sh -d600 D:\testfile.dat

Explanation of parameters:
 

  • -c25G → Size of the test file (25 GB). This should reflect the typical size of your restore points.

  • -b512k → Block size of I/O operations.

  • -w100 → 100% write test (you can adjust for read/write mix if needed).

  • -Sh → Disables hardware and software caching for accurate results.

  • -d600 → Test duration (600 seconds = 10 minutes).

Note: Using a test file that's too small can result in artificially fast results due to caching.

 

And here’s what I got back from the test:

 

 

Summary:

  • Total Data Written: ~384.7 GB

  • Write Throughput: 656.57 MiB/s (~688 MB/s)

  • IOPS: 1313.13

  • No read operations, as expected with -w100

This is a very solid performance result. Sustaining over 650 MiB/s in sequential write means the disk subsystem is not a bottleneck in my scenario.

Yep...have had to use that as well; and more recently, now that I run Linux boxes, it’s good to note (from the KB) that FIO is used for Linux. Informative KB.

Thanks for sharing Matheus!

That is a great tool to get benchmarks that will be close to what you production does.. As much as IOMeter and CrystalDiskMark can help in your trouble shooting, I usually use them for best case scenario or hero numbers.

 

Great write up!

Yep...have had to use that as well; and more recently, now that I run Linux boxes, it’s good to note (from the KB) that FIO is used for Linux. Informative KB.

Thanks for sharing Matheus!

I saw the documentation about FIO, and I’ll use it to see how it works! Thanks!

That is a great tool to get benchmarks that will be close to what you production does.. As much as IOMeter and CrystalDiskMark can help in your trouble shooting, I usually use them for best case scenario or hero numbers.

 

Great write up!

IOMeter is a great tool. I’ve never used it before, but during a conversation with IBM support, they mentioned using it.

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